Abstract:

In order to illustrate the oxidation and polymerization of estercatechins and their effects on the coloring performanceof solk, the heat stability of EGCG,GCG and EGCG was analyzed by UPLC-Q-TOF/MS. The results showed that when estercatechins were heated, their conversion rates were different. Moreover, the conversion rate of ECG was highest and GCG was the lowest when one component existed. However, when two or more ingredients coexist, their synergistic effects beween GCG and ECG were stronger and theru conversion rates were similar. The dyeing effects of EGCG, GCG and ECG in silk were also analyzed, It is  found that the catechin absorpted rate of silk was ECG>GCG> EGCG when dyeing at the same proportion, and the catechin absorpted rate of silk was nearer. Besides, it was proved that the coloring strength of EGCG and GCG were stronger when dyeing with different proportions. Through comparing, ECG was more suitable to be used as plant dyeing agent because its heat stability would not affect the adsorption rate, and its coloring degree was lower.

Key words: estercatechins, heat stability, silk, dye